The invention relates to a method of manufacturing a semiconductor device whereby a layer comprising Co or Ni is deposited on a surface of a semiconductor body which is bounded by regions of silicon and regions of an insulating material, after which the semiconductor body is heated during a heat treatment to a temperature at which the Co or Ni forming a metal silicide with the silicon, but not with the insulating material.
The silicon regions may be regions of monocrystalline as well as polycrystalline silicon, such as source and drain zones or gate electrodes of field effect transistors. The regions of insulating material may be used for insulating field effect transistors from one another or for lateral insulation of gate electrodes. They may be made of silicon oxide, nitride, or oxynitride.
After the heat treatment, any remaining Co or Ni may be selectively etched away relative to the insulating material and the silicide formed. The silicide then remains as a top layer on the silicon. The silicon has thus been provided with a highly conductive top layer in a self-registering manner.
Co and Ni silicides have the advantage that they possess the same crystal structure with practically the same dimensions as silicon, so that few mechanical stresses will arise in monocrystalline silicon upon the formation of the metal silicide. In addition, these metal silicides have a great resistance to etchants with which silicon oxide can be etched. As a result, silicon regions having a top layer of these metal silicides may be readily provided with an insulating layer of silicon oxide which has contact holes for local contacting of these regions.
A method of the kind mentioned in above is known from "Self-aligned CoSi.sub.2 and TiW(N) local interconnect in a sub-micron CMOS process", R. D. J. Verhaar et al., Appl. Surf. Sci., 38 (1989), pp. 458-466, whereby a layer of Co is provided on a semiconductor body having a surface bounded by regions of monocrystalline silicon, polycrystalline silicon, and silicon oxide. The semiconductor body is brought to a temperature of between 500.degree. and 900.degree. C. within a few seconds after the Co layer has been provided, and kept at this temperature for 30 seconds. Then Co is etched away from the surface and a second heat treatment at a temperature of 700.degree. C. is carried out for 30 seconds.
It was found to be practically impossible to provide a layer of CoSi.sub.2 by the known process described without "overgrowth" occurring, by which is meant that the growth of the metal silicide is not limited to the silicon regions, but that it also extends to on the silicon oxide regions situated immediately next to the silicon regions. Such an overgrowth may give rise to short-circuits in the semiconductor device.